Hacking Hardware Modded switch oled "failed to init eMMC"

[Ventuaer]

Hi! I recently finished modding my switch oled (after finding out that the previous modchip wasn't working, was fun :^)) booting hekate I thought the worst of it was behind me, but after trying to create the emuMMC it warned me about the slow read speeds and that the eMMC failed to init. Booting the console with volume buttons pressed shows a purple screen, which is obviously a problem with the eMMC.
I highly suspect that my soldering is at fault here, but I measured the C point and it shows the correct voltage (around ~730 mV one way, 400 ish the other, will post the correct readings tomorrow when I take it apart) . How can I further check what's wrong? The part that I am the most afraid is that the eMMC is dead. I've read upon checking the rails, but I am not certain where exactly to measure the 1.8 & 3.3 volts. I have a test bench that I can plug into it, but I am not exactly a hardware person so this goes a bit beyond me. Thanks in advance!

 

[thesjaakspoiler]

When you get a slow read speeds error, it means that the APU tried communicating with the emmc but detected that it cannot read data on one or more datalines,
The Switch uses a trick by sending data in serial from/to the emmc in order to keep the device usable.
This makes is very slow and that is why it is called slow mode.
When you get the 'eMMC failed to init' error, it means that the APU ran into an error communicating with the emmc.
That would indicate that not only some of the datalines are disconnected but also things like the clock line.
Those have no backup and fail immediately (the purple screen or that error).
If only your datalines were the problem, the Switch would work (although become very slow).

Sometimes the emmc disconnects itself slightly from the main board, disconnecting one or more datalines.
This can also happen if it got too hot, either by gaming or by too much hot air from a hot air gun.
I don't think it is a scratch on your main board as you usually would get only 1 type of error.
I don't know if a DAT0 adapter could cause this issue.

Reballing/reflowing an emmc needs the right equipment but above all the right skills to do that.
If you are not confident doing that, try reaching out to one of the skilled repair guys here.
Most of them have a mail-in service.

 

[Ventuaer]

When you get a slow read speeds error, it means that the APU tried communicating with the emmc but detected that it cannot read data on one or more datalines,
The Switch uses a trick by sending data in serial from/to the emmc in order to keep the device usable.
This makes is very slow and that is why it is called slow mode.
When you get the 'eMMC failed to init' error, it means that the APU ran into an error communicating with the emmc.
That would indicate that not only some of the datalines are disconnected but also things like the clock line.
Those have no backup and fail immediately (the purple screen or that error).
If only your datalines were the problem, the Switch would work (although become very slow).

Sometimes the emmc disconnects itself slightly from the main board, disconnecting one or more datalines.
This can also happen if it got too hot, either by gaming or by too much hot air from a hot air gun.
I don't think it is a scratch on your main board as you usually would get only 1 type of error.
I don't know if a DAT0 adapter could cause this issue.

Reballing/reflowing an emmc needs the right equipment but above all the right skills to do that.
If you are not confident doing that, try reaching out to one of the skilled repair guys here.
Most of them have a mail-in service.

Thank you greatly for the reply. I have reballed things before, though, not sure if we have a stencil for this eMMC. In case I fail, though, would i be able to buy another eMMC and swap it in place? I read upon someone being able to use a Samsung eMMC, just seems a bit sketchy .

Though, I did not use hot air to solder in the C/DAT0 point, only soldering iron, and then some very low temp (150-160C) hot air to dry it out. Maybe trying to push in the flex damaged the tin in between?



Also, I've read online that it might be because of a faulty 4.7K resistor (I suppose the A point). Would that it be possible to try to fix that, or my problems point to a faulty eMMC (either the chip itself or soldering)?
EDIT: measuring it I get a reading of around 3K so I suppose that is not supposed to be that "low"
EDITV2: took it down and it seemed that it's resistance is 0. How odd. I will order some more resistors, but damn, they are small..

 

[Ventuaer]

Final update: replacing the A point resistor fixed it all, it now boots and no error with hekate trying to create emuMMC! Did not need to touch the eMMC at all, it was probably from me nudging and desoldering the resistor a bit. Probably.
Still weird that the resistor read 0 ohms when measured. Replacing it with a fresh 4.7KOhm fixed it.